#include <bits/stdc++.h>
using namespace std;

int main() {
  ios::sync_with_stdio(false);

  int64_t N; { cin >> N; }

  for (int i = 2; (int64_t) i * i <= N; ++i) {
    int64_t n = N;
    int h = n % i;
    bool ok = true;
    for (; n; n /= i) ok &= h == n % i;
    if (ok) { cout << i << endl; return 0; }
    if (N % i == 0 && N / i < i - 1) { cout << i << endl; return 0; }
  }

  cout << N - 1 << endl;
}